Yes, you can do this with PolicyPak Browser Router.
To do this, set up a rule (route) like what is seen here. Specify that the Internet Security Zone is set to BLOCK.
Then, make other rules which route to the websites you want. Finally, ensure your blocking policy is LAST in the list, so all whitelist items will process before the BLOCK item.

If multiple browsers are installed but you want to (generally) restrict users to a specific one, you can create a Browser Router Policy to accomplish this.
First, choose a common page to start each browser on, for example google.com or a corporate home page.
Then configure each browser to open this page every time it’s started. You simply use PolicyPak Application Settings Manager (not PolicyPak Browser Router) to set the following values.
Firefox:
Chrome:
Internet Explorer:
Now let’s create a Policy that always opens a specific browser when a specific page is requested, in our case, the home page we configured above.
In this example, anytime someone starts Firefox or Internet Explorer, Browser Router will immediately close that browser and open Chrome.